User blog comment:CrazyCombo/Why in the name of hell../@comment-205.174.117.254-20100511124736/@comment-1512913-20120704121748

In my opinion it exactly is, even not taking Capcom employees and the novel into consideration, the game itself gives enough hints that Dante knows who Nero is and are related.

Also a writer for 2 games and 2 more people that were working on the games sure know well, there's no reason to doubt such statements ... the questionable thing is if Capcom plan on keeping it such way, cause as you said retcons are possible and all ... so for the time being, Nero is hinted to be Vergil's son for as long till Capcom either confirms it "officially" or denies it, but they haven't done as such yet.

Unless they put out some Metal Gear crap like "Sparda's clone" or "3rd son" then there are enough hints for him being Vergil's son as Dante has children none.